The reactant in the chemical reaction 6H2O + 6CO2 ---> C6H12O6 + 6O2 is 6H20 + 6CO2. Remember that the reactant is always at the left side of the equation. So the correct answer is 6H20 + 6CO2 since it's in the left of the equation. I hope this answer helped you.
When two carbon atoms are covalently bonded together, they try to achieve an octet structure so their electrons are 4 in number while each of them donates their remaining 2 so they end up sharing 4.
